Centrifugal separator control



A ril 28, 1970 H. HEMFORT 3,508,704

CENTRIFUGAL SEPARATOR CONTROL Filed Feb. 6, 1968 INVENTOR HEINRICHHEMFORT United States Patent 3,508,704 CENTRIFUGAL SEPARATOR CONTROLHeinrich Hemfort, Oelde, Westphalia, Germany, assignor to WestfaliaSeparator A.G., Oelde, Westphalia, Germany, a corporation of GermanyFiled Feb. 6, 1968, Ser. No. 703,364 Claims priority, applicationGermany, Feb. 8, 1967, W 43,319 Int. Cl. B04b 11/04 U.S. Cl. 233-20 7Claims ABSTRACT OF THE DISCLOSURE In controlling the desludging cycle ofa centrifugal bowl of the self-opening type by sensing the level ofliquid flowing through a holdup chamber which rotates with the bowl andis in communication with the sludge chamber of the bowl, false signalscaused by foam are avoided by dividing the chamber into two compartmentsby a radially extending partition. The liquid is introduced into thefirst compartment and passes from the bottom the first compartment tothe second compartment. The height of the first compartment is less thanthe height of the second compartment and accordingly foam overflows fromthe first compartment and does not get into the second compartment.

US. Patent 3,301,476 relates to an apparatus for emitting a signal or acontrolling pulse when a specifically heavier component gathering in thesludge chamber at the periphery of the separating chamber of acentrifugal bowl, reaches a predetermined level. The instant inventionis an improvement on the apparatus of said patent.

This prior-art apparatus is characterized by an element which isdisposed in a central chamber located intermediate the separatingchamber and the skimming chamber, and emits a signal Whenever theelement comes in contact with the free level of the sensing liquid fedto the sludge chamber from the central chamber. This occurs when thesludge separated from the liquid being processed has reached apreviously determined amount, thereby changing the pressure and fiowconditions in the passages for the feed of the sensing liquid.

It has now developed that, in the centrifugal treatment of foam-formingliquids, a sensitive transducer will respond as soon as it comes incontact with the foam floating on the liquid. The desludging operationis then started before the specifically heavier component of thematerial being processed reaches the openings of the passages conductingthe sensing liquid into the sludge chamber. In the case of particularlyheavily foaming liquids, the emission of an impulse may even take placebefore any appreciable quantity of a specifically heavier component hascollected in the sludge chamber. Under certain circumstances thisconsiderably shortens the spinning periods between desludging cycles andincreases the losses of the liquid being centrifuged, because a largeamount of liquid is always ejected with the solids through the openingsin the drum mantle.

One element that causes such misfunctioning on account of itssensitivity is, for example, an electrical sensing means which is set ata higher electrical potential than the mass of the drum and starts thedesludging cycle when a conductive connection is produced between thesensing means and the mass of the drum. Foam or splashing liquid maycause such an element to respond faultily.

The invention is aimed at eliminating these disadvantages and designingthe apparatus for the emission of the controlling impulse in such amanner that premature operation by foam or by splashing is prevented.

The invention is characterized by the combination of the followingfeatures:

3,508,704 Patented Apr. 28, 1970 (l) The central chamber is divided intotwo chambers by a partition provided with holes in the outer part.

(2) The sensing liquid feed passageway empties into the upper chamber.

(3) The lower chamber communicates with the sludge chamber throughpassages.

(4) The upper chamber is separated from the chamber for collecting thepurified liquid by a battle Whose distance from the axis of rotation isgreater than that of the partition between the two portions of thecentral chamber.

The foam collecting on the liquid in the upper chamber then passes overthe battle located at the greater distance from the axis of rotation,into the chamber for collecting the purified liquid, and is thereby keptaway from the lower chamber in which the sensing means is disposed.

In the case of particularly heavily foaming liquids it is desirable toplace the overflow of the collecting chamber for purified liquid at astill greater distance from the axis of rotation so that the foam can bedischarged into a catcher surrounding the drum before it reaches theinner margin of the partition between the two portions of the centralchamber.

Another feature of the invention thus consists in the fact that theoverflow of the collecting chamber for the purified liquid is locatedfarther from the axis of rotation than the bafile separating thisgathering chamber from the chamber for the sensing liquid.

Thus the invention is directed to an improvement in centrifugalseparators of the self-opening type having a drum with a sludgecollection chamber at the periphery of the separating chamber forreceiving specifically heavier material centrifuged out of the liquid.The drum is mounted for rotation about an axis and includes a holdupchamber for holdup of a sensing liquid. The holdup chamber is disposedadjacent the axis for rotation, and has an inlet and an outlet, thelatter being communicated with the sludge collection chamber fortransfer of sensing liquid from the holdup chamber to the sludgecollection chamber. A transducer is disposed in the holdup chamber foractuation by the sensing liquid when this liquid reaches a preselectedlevel. The level of the sensing liquid is shifted inward, when thedischarge openings are clogged by specifically heavier materialcollecting in the sludge chamber of the drum. Actuation of thetransducer causes control means to operate for control of thecentrifuging. According to the invention, a radially extending partitionis disposed in the holdup chamber, dividing that chamber into a firstcompartment which includes the inlet of the holdup chamber, and a secondcompartment which includes the outlet of the holdup chamber. Thepartition has an opening disposed outwardly of the inner end thereof andcommunicating the two compartments. The transducer is disposed in thesecond compartment, and the height of the first compartment is less thanthe height of the second compartment. By reason of this construction,foam will overflow from the first compartment and will not get into thesecond compartment.

An example of the embodiment of the invention is represented in thedrawing, in which:

FIG. 1 shows the upper portion of a self-cleaning clarifying centrifugewith the apparatus according to the invention and a skimming disc as theclarified liquid removing means; and

FIG. 2 shows the central portion on a larger scale.

The liquid containing solids is fed continually to the drum throughconduit 1 and infeed tube 2. The specifically heavier contaminantsseparated from the liquid, collect in the sludge chamber 3. Theclarified liquid passes from the central portion of the separatingchamber through passages 4 in to the skimming chamber 5 and is pumpedout under pressure by skimming disc 6 through conduit 7.

A small portion of the clarified liquid is carried back into sludgechamber 3 through passages 8 and 8a in order to serve as the sensingliquid. Passages 8 emerge from a central chamber or holdup chamberwhich, according to the invention is bipartite. The upper compartment 9receives the sensing liquid brought in through passage 10. Itcommunicates with the lower compartment 12 through outer holes 11, andwith the skimming chamber through the annular gap 13. The electricalsensing means 14, which is surrounded by insulating material 15, extendsinto chamber 12, and is disposed outwardly of the inner end of partition19.

During the centrifuging, the same liquid level establishes itself incompartments 9 and 12 on account of the communicating connection betweenthem, as indicated by the dash-dotted line 16. The foam floating on theliquid in compartment 9 cannot pass through holes 11 into compartment12. Due to the fact that the baffle 18 is farther away from the axis ofrotation than wall 19 separating compartments 9 and 12 from one another,the height of compartment 9 is less than the height of compartment 12,and therefore the foam passes out of compartment 9 over bafile 18 intothe skimming chamber -5. In the case of especially high-foaming liquids,it is desirable to construct the cover 17 of the collecting chamber 5 insuch a manner that the overflow of this chamber will be at a greaterdistance from the axis of rotation than bafiie 18, i.e., so that theheight of chamber 5 is less than the height of compartment 9.

When the solids deposited in sludge chamber 3 prevent the emergence ofthe sensing liquid from passage 8a, then the free liquid level in theintercommunicating chambers 9 and 12 shifts. As soon as the liquidcontacts the sensing means 14, a circuit is closed. The electric currentthat is thus made to flow can, for example, cause a relay in a switchbox 20 (FIG. 1) to respond, which imparts the pulse to controller 21 tostart the desludging cycle, e.g., to lower the gate 22 to permit flowthrough the discharge openings 23.

While the invention has been described with respect to particularembodiments thereof, these embodiments are merely representative and donot serve to set forth the limits of the invention.

What is claimed is:

1. In a centrifugal separator comprising:

(a) a drum with a sludge collection chamber at its periphery forreceiving specifically heavier material centrifuged out of a liquid, thedrum being mounted for rotation about an axis for the centrifuging;

(b) a holdup chamber for holdup of a sensing liquid, the holdup chamberbeing disposed adjacent said axis for rotation with the drum;

(c) said holdup chamber having an inlet and an outlet, the latter beingcommunicated with the sludge collection chamber for transfer of asensing liquid from the holdup chamber to the sludge collection chamber,whereby the liquid level in the holdup chamber is shifted inward, whenthe discharge openings are clogged by specifically heavier materialcollecting in the sludge chamber;

(d) a transducer disposed in the holdup chamber for actuation by theliquid when the liquid reaches a preselected level;

(e) control means for response to actuation of the transducer andcontrol of operation of the centrifuge;

the improvement which comprises:

(f) a radially extending partition in the holdup chamber dividing theholdup chamber into a first compartment including said inlet and asecond compartment including said outlet, said partition having anopening disposed outwardly of the inner end of the partition,communicating the two compartments, the transducer benig disposed insaid second compartment, the height of the first compartment being lessthan the height of the second compartment.

2. Centrifuge according to claim 1, wherein the transducer is disposedoutwardly of the inner end of the partition.

3. Centrifuge according to claim 2, wherein said outlet of the holdupchamber is disposed adjacent the outer end of the chamber in the secondcompartment and communicates with the sludge collection chamber.

4. Centrifuge according to claim 3, the compartment in which thetransducer is located being disposed beneath the other compartment.

5. Centrifuge according to claim 2, and a skimming chamber communicatingwith the first compartment so that overflow from the first compartment,enters into the skimming chamber, the height of the skimming chamberbeing less than the height of said first compartment.

6. Centrifuge according to claim 3, and a skimming chamber communicatingwith the first compartment so that overflow from the first compartment,enters into the skimming chamber, the height of the skimming chamberbeing less than the height of said first compartment.

7. Centrifuge according to claim 4, and a skimming chamber communicatingwith the first compartment so that overflow from the first compartment,enters into the skimming chamber, the height of the skimming chamberbeing less than the height of said first compartment.

References Cited UNITED STATES PATENTS 3,135,691 6/1964 Hemfort 233-193,167,509 1/1965 Steinackcr 233-20 3,301,476 1/ 1967 Hernfort 233-203,396,910 8/1968 Steinacker 233-20 WILLIAM I. PRICE, Primary Examiner

